J Neurol (2016) 263:843–854 DOI 10.1007/s00415-015-7962-6 REVIEW Mal de debarquement syndrome: a systematic review 1,2,3 2,4 1,3,5 Angelique Van Ombergen • Vincent Van Rompaey • Leen K. Maes • 1,2,4 1,3 Paul H. Van de Heyning • Floris L. Wuyts Received: 7 October 2015 / Revised: 27 October 2015 / Accepted: 28 October 2015 / Published online: 11 November 2015 Ó The Author(s) 2015. This article is published with open access at Springerlink.com Abstract Mal de debarquement (MdD) is a subjective debarquement’’ and ‘‘sea legs’’. Based on this, we suggest a perception of self-motion after exposure to passive motion, list of criteria that could aid healthcare professionals in the in most cases sea travel, hence the name. Mal de debar- diagnosis of MdDS. Further research needs to address the quement occurs quite frequently in otherwise healthy blank gaps by addressing how prevalent MdD(S) really is, individuals for a short period of time (several hours). by digging deeper into the underlying pathophysiology and However, in some people symptoms remain for a longer setting up prospective, randomized placebo-controlled period of time or even persist and this is then called mal de studies to evaluate the effectiveness of possible treatment debarquement syndrome (MdDS). The underlying patho- strategies. genesis is poorly understood and therefore, treatment options are limited. In general, limited studies have focused Keywords Mal de debarquement Á Sea legs Á Mal de on the topic, but the past few years more and more interest debarquement syndrome Á Systematic review has been attributed to MdDS and its facets, which is reflected by an increasing number of papers. Till date, some interesting reviews on the topic have been published, Introduction but a systematic review of the literature is lacking and could help to address the shortcomings and flaws of the The first real recognition of mal de debarquement (MdD) current literature. We here present a systematic review of as a clinical syndrome only occurred in 1987 by Brown and MdD(S) based on a systematic search of medical databases Baloh [1], preceded by allusions made by Darwin and employing predefined criteria, using the terms ‘‘mal de Irwin [2, 3]. Mal de debarquement, also known as ‘sea legs’ [4], rocking dizziness [5] or mal de debarquement syndrome & Angelique Van Ombergen (MdDS) [1, 6], is a subjective perception of self-motion [email protected] after exposure to passive motion and can sometimes be 1 accompanied by actual postural disturbances. In most Antwerp University Research Centre for Equilibrium and cases, MdD (which freely translates to ‘‘sickness after Aerospace (AUREA), University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium disembarkment’’) occurs after sea travel; however, MdD can also occur after air or land travel [7, 8]. The underlying 2 Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium pathogenesis of MdD is unclear and it is considered a rare disease [1, 9–11]. In any case, it is important to make a 3 Faculty of Sciences, Department of Physics, University of Antwerp, Antwerp, Belgium distinction between transient MdD symptoms (\48 h) [12] and persistent MdDS ([3 days up to several years) [1, 13], 4 Department of Otorhinolaryngology, Antwerp University Hospital, Wilrijkstraat 10, Edegem (Antwerp), Belgium as the latter is pathological, while transient MdD is a common phenomenon (e.g., in naval personnel) and occurs 5 Faculty of Medicine and Health Sciences, Department of Speech, Language and Hearing Sciences, Ghent University, frequently with reported numbers between 72 and 80 % [4, Ghent, Belgium 12, 14, 15]. 123 844 J Neurol (2016) 263:843–854 Clinically, patients experience a rocking, bobbing or and ‘‘sea legs’’ without restriction of publication date. Ref- swaying sensation which is often accompanied by unsteadi- erence lists from retrieved articles were also searched man- ness and disequilibrium that occurs persistently after cessation ually for relevant publications on either mal de of the exposed passive motion stimulus [1, 16]. A high asso- debarquement that were not included in the lists created ciation of MdDS and headache [17] and migraine [13]has through the Medline database. Research abstracts from been postulated, especially in patients who develop sponta- meeting proceedings or unpublished studies were not neous MdDS episodes [13]. Previous studies also found included. The search was last updated on 18 September 2015. associations between MdDS and motion sickness [4], [13, 18], The title and abstract of all of the articles yielded by the increased self-motion sensitivity [13] and increased visual search were screened by two independent reviewers and sensitivity [13]. Consequently, MdDS is associated with a selected using predetermined criteria. Non-English studies lower quality of life (QoL), higher anxiety and depression and case and anecdotal reports were excluded. Other exclu- rates and has a significant socio-economic impact [19–21]. In sion criteria were a lack of original patient data (e.g., reviews) general, no structural abnormalities are found on standard or duplications of data published in other included papers. brain magnetic resonance imaging (MRI) scans and inner ear Full-text screening was applied to all abstracts consid- function tests are normal [1] and therefore, this is often used as ered eligible by at least one reviewer. an inclusion criterion in MdDS studies [22–24]. There is a well-documented female preponderance for MdD [1, 13, 25]. Data extraction and analysis Treatment options are limited, but some pharmaceutical agents (e.g., benzodiazepines, selective serotonin reuptake A table (Table 1) was constructed to summarize relevant inhibitors) [13, 25], stress relievement therapy [13] and results from the selected studies. Study designs, objectives vestibular rehabilitation have been reported as being bene- and outcome measurements were discrepant and not ficial [1, 9, 13, 25]. More recently, promising results have amenable to quantitative analysis. Data were classified and been achieved by means of neuromodulation [22, 24, 26, 27] analyzed qualitatively. (i.e., repetitive transcranial magnetic stimulation (rTMS)) Ethics committee authorization was not required as this and modulation of the vestibulo-ocular reflex (VOR) [28], study reviewed previously published data. which is assumed to be maladapted in MdDS [29, 30]. Over the past decades, more studies were dedicated to MdDS and its clinical representation [1, 5, 9, 13, 16, 19, Results 25], socio-economic impact [19–21], underlying patho- physiology [19, 23, 31–33] and possible treatment strate- The database search yielded 48 citations and hand search gies [18, 22, 24, 28]. Unfortunately, the literature is still added 5 articles. The oldest article was published in 1987 scarce and suffers from the lack of generalization due to by Brown and Baloh [1] and the most recent was published case reports, small-sample studies and the absence of case– in 2015 by Nwagwu and colleagues [35]. Full-text review control and placebo-controlled studies. Although interest- resulted in the exclusion of 34 articles, resulting in 19 ing reviews on the topic are available [6, 8, 34], a sys- eligible articles. Seven articles reported findings related to tematic review on existing MdD and MdDS literature is MdD from a healthy population (i.e., crew members of lacking. A thorough synthesis could help to efficiently set- seagoing vessels [12, 14, 16], sailors [15], staff and pas- up and conduct future research on the topic. sengers on a dive trip [36], students taking part in an The aim of the present study was twofold: (a) to conduct education program at sea [4] and healthy participants a systematic review of studies describing the epidemiology, exposed to a ship motion simulator [18] ), while the other diagnostic procedure, the (neuro)pathophysiology and 12 articles report surveys and experiments in patients [1, treatment options of this rare and poorly understood entity 13, 17, 19–23, 25, 28, 31, 37]. A summary of the articles and (b) to identify flaws in the existing literature con- that were selected for inclusion can be found in Table 1.A cerning mal de debarquement and concurrently summarize qualitative synthesis and critical appraisal of the patient- future research opportunities. related studies can be found in Table 2. The percentage of agreement between the two reviewers was high (96.3 %), yielding an interrater agreement kappa Materials and methods coefficient of 0.92 (SE = 0.054). Search strategy Epidemiological and demographic data The Medline (PubMed) and EMBASE databases were MdDS, as seen in its persistent form in patients, is con- searched for papers using the term ‘‘mal de debarquement’’ sidered a rare disease and prevalence numbers in the 123 J Neurol (2016) 263:843–854 845 Table 1 Qualitative synthesis on the demographic features and inclusion criteria of the included MdD(S) studies Study Pro-(p) or Healthy Subjects M/F Mean age Inclusion criteria retrospective individuals (n) (SD) (years) (r) (h)/patients (p) Brown and Baloh r p 6 1/5 50.8 (14.3)° nc [1] Gordon et al. [13] r h 234 234/0 20.5 (nd) n/a Murphy [8] r p 4 0/4 nd nc Gordon et al. [11] r h 116 116/0 nd n/a Cohen [14] r h 59 nd nd n/a Hain et al. [24] r p 27 1/26 49.3 (10.3) (a) Diagnosis of MdDS by at least 1 physician (b) Sensation of rocking or swaying that persisted at least 1 month following a 4-h or longer exposure to motion on an airplane or boat Nachum et al. [15] p h 34 34/0 nd, age n/a range: (18–22) Cha et al. [12] r p 64 16/48 nd Internal sensation of motion such as rocking, swaying or bobbing lasting at least 3 days after exposure to passive motion Gibbs et al.